/*
 * Copyright (c) 2007, 2015, Oracle and/or its affiliates. All rights reserved.
 * ORACLE PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
 */
/*
 * Copyright 2001-2004 The Apache Software Foundation.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
/*
 * $Id: EqualityExpr.java,v 1.2.4.1 2005/09/12 10:16:52 pvedula Exp $
 */

package com.sun.org.apache.xalan.internal.xsltc.compiler;

import com.sun.org.apache.bcel.internal.generic.BranchHandle;
import com.sun.org.apache.bcel.internal.generic.BranchInstruction;
import com.sun.org.apache.bcel.internal.generic.ConstantPoolGen;
import com.sun.org.apache.bcel.internal.generic.GOTO;
import com.sun.org.apache.bcel.internal.generic.IFEQ;
import com.sun.org.apache.bcel.internal.generic.IFNE;
import com.sun.org.apache.bcel.internal.generic.IF_ICMPEQ;
import com.sun.org.apache.bcel.internal.generic.IF_ICMPNE;
import com.sun.org.apache.bcel.internal.generic.INVOKESTATIC;
import com.sun.org.apache.bcel.internal.generic.INVOKEVIRTUAL;
import com.sun.org.apache.bcel.internal.generic.InstructionList;
import com.sun.org.apache.bcel.internal.generic.PUSH;
import com.sun.org.apache.xalan.internal.xsltc.compiler.util.BooleanType;
import com.sun.org.apache.xalan.internal.xsltc.compiler.util.ClassGenerator;
import com.sun.org.apache.xalan.internal.xsltc.compiler.util.IntType;
import com.sun.org.apache.xalan.internal.xsltc.compiler.util.MethodGenerator;
import com.sun.org.apache.xalan.internal.xsltc.compiler.util.NodeSetType;
import com.sun.org.apache.xalan.internal.xsltc.compiler.util.NodeType;
import com.sun.org.apache.xalan.internal.xsltc.compiler.util.NumberType;
import com.sun.org.apache.xalan.internal.xsltc.compiler.util.RealType;
import com.sun.org.apache.xalan.internal.xsltc.compiler.util.ReferenceType;
import com.sun.org.apache.xalan.internal.xsltc.compiler.util.ResultTreeType;
import com.sun.org.apache.xalan.internal.xsltc.compiler.util.StringType;
import com.sun.org.apache.xalan.internal.xsltc.compiler.util.Type;
import com.sun.org.apache.xalan.internal.xsltc.compiler.util.TypeCheckError;
import com.sun.org.apache.xalan.internal.xsltc.runtime.Operators;

/**
 * @author Jacek Ambroziak
 * @author Santiago Pericas-Geertsen
 * @author Morten Jorgensen
 * @author Erwin Bolwidt <ejb@klomp.org>
 */
final class EqualityExpr extends Expression {

  private final int _op;
  private Expression _left;
  private Expression _right;

  public EqualityExpr(int op, Expression left, Expression right) {
    _op = op;
    (_left = left).setParent(this);
    (_right = right).setParent(this);
  }

  public void setParser(Parser parser) {
    super.setParser(parser);
    _left.setParser(parser);
    _right.setParser(parser);
  }

  public String toString() {
    return Operators.getOpNames(_op) + '(' + _left + ", " + _right + ')';
  }

  public Expression getLeft() {
    return _left;
  }

  public Expression getRight() {
    return _right;
  }

  public boolean getOp() {
    return (_op != Operators.NE);
  }

  /**
   * Returns true if this expressions contains a call to position(). This is
   * needed for context changes in node steps containing multiple predicates.
   */
  public boolean hasPositionCall() {
    if (_left.hasPositionCall()) {
      return true;
    }
    if (_right.hasPositionCall()) {
      return true;
    }
    return false;
  }

  public boolean hasLastCall() {
    if (_left.hasLastCall()) {
      return true;
    }
    if (_right.hasLastCall()) {
      return true;
    }
    return false;
  }

  private void swapArguments() {
    final Expression temp = _left;
    _left = _right;
    _right = temp;
  }

  /**
   * Typing rules: see XSLT Reference by M. Kay page 345.
   */
  public Type typeCheck(SymbolTable stable) throws TypeCheckError {
    final Type tleft = _left.typeCheck(stable);
    final Type tright = _right.typeCheck(stable);

    if (tleft.isSimple() && tright.isSimple()) {
      if (tleft != tright) {
        if (tleft instanceof BooleanType) {
          _right = new CastExpr(_right, Type.Boolean);
        } else if (tright instanceof BooleanType) {
          _left = new CastExpr(_left, Type.Boolean);
        } else if (tleft instanceof NumberType ||
            tright instanceof NumberType) {
          _left = new CastExpr(_left, Type.Real);
          _right = new CastExpr(_right, Type.Real);
        } else {          // both compared as strings
          _left = new CastExpr(_left, Type.String);
          _right = new CastExpr(_right, Type.String);
        }
      }
    } else if (tleft instanceof ReferenceType) {
      _right = new CastExpr(_right, Type.Reference);
    } else if (tright instanceof ReferenceType) {
      _left = new CastExpr(_left, Type.Reference);
    }
    // the following 2 cases optimize @attr|.|.. = 'string'
    else if (tleft instanceof NodeType && tright == Type.String) {
      _left = new CastExpr(_left, Type.String);
    } else if (tleft == Type.String && tright instanceof NodeType) {
      _right = new CastExpr(_right, Type.String);
    }
    // optimize node/node
    else if (tleft instanceof NodeType && tright instanceof NodeType) {
      _left = new CastExpr(_left, Type.String);
      _right = new CastExpr(_right, Type.String);
    } else if (tleft instanceof NodeType && tright instanceof NodeSetType) {
      // compare(Node, NodeSet) will be invoked
    } else if (tleft instanceof NodeSetType && tright instanceof NodeType) {
      swapArguments();    // for compare(Node, NodeSet)
    } else {
      // At least one argument is of type node, node-set or result-tree

      // Promote an expression of type node to node-set
      if (tleft instanceof NodeType) {
        _left = new CastExpr(_left, Type.NodeSet);
      }
      if (tright instanceof NodeType) {
        _right = new CastExpr(_right, Type.NodeSet);
      }

      // If one arg is a node-set then make it the left one
      if (tleft.isSimple() ||
          tleft instanceof ResultTreeType &&
              tright instanceof NodeSetType) {
        swapArguments();
      }

      // Promote integers to doubles to have fewer compares
      if (_right.getType() instanceof IntType) {
        _right = new CastExpr(_right, Type.Real);
      }
    }
    return _type = Type.Boolean;
  }

  public void translateDesynthesized(ClassGenerator classGen,
      MethodGenerator methodGen) {
    final Type tleft = _left.getType();
    final InstructionList il = methodGen.getInstructionList();

    if (tleft instanceof BooleanType) {
      _left.translate(classGen, methodGen);
      _right.translate(classGen, methodGen);
      _falseList.add(il.append(_op == Operators.EQ ?
          (BranchInstruction) new IF_ICMPNE(null) :
          (BranchInstruction) new IF_ICMPEQ(null)));
    } else if (tleft instanceof NumberType) {
      _left.translate(classGen, methodGen);
      _right.translate(classGen, methodGen);

      if (tleft instanceof RealType) {
        il.append(DCMPG);
        _falseList.add(il.append(_op == Operators.EQ ?
            (BranchInstruction) new IFNE(null) :
            (BranchInstruction) new IFEQ(null)));
      } else {
        _falseList.add(il.append(_op == Operators.EQ ?
            (BranchInstruction) new IF_ICMPNE(null) :
            (BranchInstruction) new IF_ICMPEQ(null)));
      }
    } else {
      translate(classGen, methodGen);
      desynthesize(classGen, methodGen);
    }
  }

  public void translate(ClassGenerator classGen, MethodGenerator methodGen) {
    final ConstantPoolGen cpg = classGen.getConstantPool();
    final InstructionList il = methodGen.getInstructionList();

    final Type tleft = _left.getType();
    Type tright = _right.getType();

    if (tleft instanceof BooleanType || tleft instanceof NumberType) {
      translateDesynthesized(classGen, methodGen);
      synthesize(classGen, methodGen);
      return;
    }

    if (tleft instanceof StringType) {
      final int equals = cpg.addMethodref(STRING_CLASS,
          "equals",
          "(" + OBJECT_SIG + ")Z");
      _left.translate(classGen, methodGen);
      _right.translate(classGen, methodGen);
      il.append(new INVOKEVIRTUAL(equals));

      if (_op == Operators.NE) {
        il.append(ICONST_1);
        il.append(IXOR);                        // not x <-> x xor 1
      }
      return;
    }

    BranchHandle truec, falsec;

    if (tleft instanceof ResultTreeType) {
      if (tright instanceof BooleanType) {
        _right.translate(classGen, methodGen);
        if (_op == Operators.NE) {
          il.append(ICONST_1);
          il.append(IXOR); // not x <-> x xor 1
        }
        return;
      }

      if (tright instanceof RealType) {
        _left.translate(classGen, methodGen);
        tleft.translateTo(classGen, methodGen, Type.Real);
        _right.translate(classGen, methodGen);

        il.append(DCMPG);
        falsec = il.append(_op == Operators.EQ ?
            (BranchInstruction) new IFNE(null) :
            (BranchInstruction) new IFEQ(null));
        il.append(ICONST_1);
        truec = il.append(new GOTO(null));
        falsec.setTarget(il.append(ICONST_0));
        truec.setTarget(il.append(NOP));
        return;
      }

      // Next, result-tree/string and result-tree/result-tree comparisons

      _left.translate(classGen, methodGen);
      tleft.translateTo(classGen, methodGen, Type.String);
      _right.translate(classGen, methodGen);

      if (tright instanceof ResultTreeType) {
        tright.translateTo(classGen, methodGen, Type.String);
      }

      final int equals = cpg.addMethodref(STRING_CLASS,
          "equals",
          "(" + OBJECT_SIG + ")Z");
      il.append(new INVOKEVIRTUAL(equals));

      if (_op == Operators.NE) {
        il.append(ICONST_1);
        il.append(IXOR);                        // not x <-> x xor 1
      }
      return;
    }

    if (tleft instanceof NodeSetType && tright instanceof BooleanType) {
      _left.translate(classGen, methodGen);
      _left.startIterator(classGen, methodGen);
      Type.NodeSet.translateTo(classGen, methodGen, Type.Boolean);
      _right.translate(classGen, methodGen);

      il.append(IXOR); // x != y <-> x xor y
      if (_op == Operators.EQ) {
        il.append(ICONST_1);
        il.append(IXOR); // not x <-> x xor 1
      }
      return;
    }

    if (tleft instanceof NodeSetType && tright instanceof StringType) {
      _left.translate(classGen, methodGen);
      _left.startIterator(classGen, methodGen); // needed ?
      _right.translate(classGen, methodGen);
      il.append(new PUSH(cpg, _op));
      il.append(methodGen.loadDOM());
      final int cmp = cpg.addMethodref(BASIS_LIBRARY_CLASS,
          "compare",
          "("
              + tleft.toSignature()
              + tright.toSignature()
              + "I"
              + DOM_INTF_SIG
              + ")Z");
      il.append(new INVOKESTATIC(cmp));
      return;
    }

    // Next, node-set/t for t in {real, string, node-set, result-tree}
    _left.translate(classGen, methodGen);
    _left.startIterator(classGen, methodGen);
    _right.translate(classGen, methodGen);
    _right.startIterator(classGen, methodGen);

    // Cast a result tree to a string to use an existing compare
    if (tright instanceof ResultTreeType) {
      tright.translateTo(classGen, methodGen, Type.String);
      tright = Type.String;
    }

    // Call the appropriate compare() from the BasisLibrary
    il.append(new PUSH(cpg, _op));
    il.append(methodGen.loadDOM());

    final int compare = cpg.addMethodref(BASIS_LIBRARY_CLASS,
        "compare",
        "("
            + tleft.toSignature()
            + tright.toSignature()
            + "I"
            + DOM_INTF_SIG
            + ")Z");
    il.append(new INVOKESTATIC(compare));
  }
}
